Apparatuses of the kind here of interest serve for processing workpieces containing plastics material, especially such as consist wholly or in part of thermoplastic plastics, by welding, stamping, cutting and/or bonding. The processing of the workpieces by the use of such apparatuses mostly takes place in that the workpieces are plasticised by heating. The plasticising can be effected by ultrasound (e.g. DE 100 46 451 A1), by use of hot air (e.g. DE 100 38 158 B4) or by contact with a heating element. Processing tools may for example be sonotrodes, nozzles which deliver heated gas streams, electrical heating elements or the like, wherein all these tools are preferably mounted on feed units and can thus be moved to and fro in the direction of the workpieces, in order to start and end the processing operations.
Processing apparatuses of this kind are complex installations which are used in multifarious ways, e.g. in the automobile industry and there in particular for the manufacture of fenders, door and trunk claddings, instrument panels, consoles or the like from polypropylenes and other thermoplastic plastics.
A particular problems is posed by the retooling of such processing apparatuses when changing the workpieces, since both the workpiece receptacles and the tools which are used, or their positioning have to be changed. Apparatuses of the kind initially specified are therefore known, especially so-called cassette machines, which are provided with interchangeable devices, denoted cassettes or interchangeable modules. These contain the necessary receptacles and tools in a manner adapted to a selected processing task and can be fitted or be exchanged when required for another one comparatively quickly in the processing apparatus involved. It is advantageous if the devices denoted throughout below as interchangeable modules can be assembled and pre-mounted largely outside the processing apparatus, so that only short downtimes are needed for the processing apparatus. It is further advantageous that these apparatuses comprises a processing station and a loading and unloading station removed therefrom, in which the workpieces can be loaded in the receptacles and unloaded therefrom without danger to the operator. The receptacle can to this end be moved automatically to and fro between the loading and unloading station and the processing station. However the previously known processing apparatuses of the kind initially specified are characterized by two features found to be disadvantageous.
One feature lies in that the interchangeable module has to be brought to the processing apparatus by means of auxiliary means in the form of a crane, a workpiece truck or the like and then introduced into the processing machine, if required with the use of a reversing device rotatable through 180°.
The use of such auxiliary means involves awkward manipulations when loading, fixing, unloading or the like.
Another feature, likewise not inconsiderable, lies in that the interchangeable module is composed of two elements separable from one another. One of these elements, which mostly forms the bottom of the interchangeable module and carries the workpiece receptacle, is mounted on a slide table of the apparatus movable to and fro between the processing station and the loading and unloading station. On the other hand, the other element forming the remaining part of the interchangeable module and carrying the tools, their feed units and other components is mounted on a so-called bridge of the apparatus, by means of which it is moved to and fro perpendicular to the receptacle, in order to provide enough space between the latter and the workpieces for loading the workpieces, especially when bulky or strongly curved workpieces are involved. On account of this construction it is on the one hand necessary, if needed apart from the tools, to move also a larger, heavy frame section of the interchangeable module, e.g. up to 500 kg, which requires correspondingly designed frame parts and drive units. On the other hand the two elements have to be positioned accurately after their transfer into the processing station and be brought into a predetermined position relative to one another, for which numerous positioning and fixing means are needed. This requires measures which appreciably increase the overall changeover time.
In addition, numerous apparatuses of the kind initially specified are known in which a basic processing unit can be associated in modular manner with a plurality of additional processing units or feed units for additional components, in order to perform several processing steps on the workpieces one after the other or to combine the workpieces with selected components. The additional processing and feed units can also be made mobile and be provided with means for coupling them to a basic processing station in correct position (e.g. DE 103 13 792 A1, DE 197 41 671 A1, DE 199 10 028 A1 or DE 34 13 255 A1). However the problem described above is not solved in any of these devices, viz. on the one hand loading and unloading the workpieces, e.g. manually, in a loading/unloading station removed from the processing station, on the other hand enabling accurate positioning of the workpieces in a processing station, which is arranged in an interchangeable module, without complicated manipulations and adjustments.
Developing from this, the object of the present invention lies in so forming the apparatus of the kind initially specified that no additional auxiliary means such as cranes, trucks or the like are needed for the changeover operation, that small changeover times and thus downtimes of the processing apparatus can be realised and that no positioning, adjusting and fixing measures requiring expensive, complicated manipulations need to be carried out.